Thermodynamic considerations have been made to extract the determining factors fbr the positive electrode potential in the lithium batteries in which the lithium-transition metal-oxygen compounds are used as the positive electrode. Interpretation has been made by dividing the contributions to the lithium chemical potential change for the electrode reaction into two terms; the stabilization energy of the double oxide from the constituent oxide and the valence stability of lithium and the transition metals, in other words, the redox term. The major factor in the ternary Li-M-O system has been found to be the redox term of the transition metal oxides; in other words, die equilibrium oxygen partial pressure of the redox equilibria of the transition metal oxide. This explains why LiCoO2 or LiNiO2 have large potentials. In the quaternary Li-M-X-O system, the stabilization energy of Li(XOm)(n) becomes an additional term. This term leads to high potentials in Fe-3(SO4)(2) or LiMVO4(M = Ni, Co).